The Spring 1999 Issue is now available To Order:

The arch offers the unique possibility of spanning sizable intervals and of carrying considerable weight without intermediate supports.  In the true brick or masonry arch, weight is supported by means of wedge-shaped construction blocks (voussoirs) that are disposed radially and held together in compression.

The most basic components of the arch are its arc, or curved profile; the sprandrel, or wall plane that covers the curvature over the arch; the voissoirs, building blocks that are usually wedge-shaped; the keystone, the central voussoir at the apex of the arch; and the impost, a block that projects from the top of a pier from which the arch might spring.  These elements are often decorated with bas-relief and sculptural motifs.